1. Field of the Invention
The present invention relates to an information data recording apparatus for a video tape recorder (VTR) having a digital format or the like, for example.
2. Description of the Prior Art
In conventional digital video tape recorders, as U.S. Pat. No. 4,799,113 describes, an input analog video signal is converted into digital data and outer code data for error correction is added to the digital data. Then, the digital data added with the outer code data is shuffled, the shuffled digital data is multiplexed, inner code data for error correction is added to the digital data thus multiplexed and the digital data added with the inner code data is processed in a channel-coding fashion. Further, the digital data that was processed in a channel-coding fashion is amplified and then supplied to a recording rotary head such that the digital data is recorded by the recording rotary head so as to form oblique video tracks.
FIG. 1 of the accompanying drawings shows a digital video tape recorder (DVTR) tape format utilized when digital data is recorded in the digital VTR. As shown in FIG. 1, in the above digital VTR, video data of one field is recorded by six video tracks.
When video data recorded on a magnetic tape is reproduced, the magnetic tape is transported in the direction shown by an open arrow in FIG. 1 and a reproducing head is rotated in the direction shown by a solid arrow in FIG. 1. More specifically, as shown in FIG. 2, a magnetic tape 14 is transported from an entrance tape guide d1 to an exit tape guide d3 and a rotary drum d2 having a reproducing head 15 mounted thereon is rotated as shown by an arrow R1 in FIG. 2. Then, magnetic head 15 sequentially scans video tracks T1, T2, T3, T4, T5, T6 to reproduce recorded video data. Then, the reproduced data or signal is equalized and amplified. The reproduced signal thus amplified is decoded, de-shuffled and the reproduced signal thus de-shuffled is error-corrected. Then, the reproduced signal thus error-corrected is error-concealed and the reproduced signal thus error-concealed is output as a digital or analog video signal.
In the above digital VTR, as shown in FIG. 3, for example, when a field 2 shown hatched (corresponding to video tracks T21 to T26) of the recorded portion recorded over three fields is edited, if the tracking is displaced forwardly, then the first video track T21 of the field 2 overlaps the video track T16 of the field 1 that is not the target field as shown by a hatched portion in FIG. 4. As a result, recorded data on the video track T16 is destroyed so that, upon playback, a signal on the video track T16 becomes erroneous.
Conversely, as shown in FIG. 5, when the field 2 shown hatched (corresponding to the video tracks T21 to T26) of the recorded portion recorded over three fields is edited, if the tracking is displaced backwardly, the last video track T26 of the field 2 overlaps a video track T31 of a field 3 that is not the target field as shown by a hatched portion. Consequently, recorded data on the video track T31 is destroyed so that, upon playback, a signal on the video track T31 becomes erroneous.
As described above, in the digital VTR in which data of one field is separated into a plurality of narrow video tracks and then recorded, if a mis-tracking occurs upon editing, data on the video track just ahead of or behind the edit point is destroyed and an error occurs. There is then the disadvantage that a reproduced picture will be deteriorated.